Magnetic properties of electrons and holes in metallic Si:P and Si:B

We present new NMR data on the P³¹ resonance in Si:P and B¹¹ resonance in Si:B for samples in the impurity concentration range from 5 ×{} 10¹⁸ to 9 ×{} 10¹⁹ cm^-3. The data give further information about the magnetic properties of the charge carriers in these metallic samples. These data, taken in conjunction with recent NMR data for Si²⁹ by Sasaki, Ikehata, and Kobayashi in Si:P in the same concentration range place certain restrictions upon models which have been introduced to interpret magnetoresistance and spin-susceptibility data. Both P³¹ and Si²⁹ data in Si:P exhibit a temperature dependence of linewidth and Knight shift for T below 4.2 K. The results are compared to the ESR spin-susceptibility measurements of Quirt and Marko and of Ue and Maekawa. It is observed that the temperature dependence of the Knight shift and linewidth can be almost entirely accounted for by the temperature dependence of the spin susceptibility. The NMR data support a simple model in which all donor electrons or acceptor holes participate in a single, interacting system. They give no confirmation to the existence of the local magnetic moments which have been invoked to explain the negative magnetoresistance in n-type heavily doped semiconductors, but can also not rule out the existence of such moments.